1. Field of the Invention
The present invention relates to semiconductor equipment, and more particularly to a gas filling chamber structure in gas filling apparatus for photomask box or wafer transport container.
2. Description of the Related Art
The photomask boxes are used in the semiconductor manufacturing process for conserving photomasks to properly protect them from contacting air or being polluted by dust when being transported between machines. In advanced semiconductor factories, the cleanliness of the photomask boxes are demanded to be better than Class 1, which is the requirement of Standard Mechanical Interface (SMIF), an IC manufacturing standard keeping the level of cleanliness of the pod.
However, in order to further improve the yield of product and reduce the cost of fabrication, not only should the requirement on cleanliness be met, but the pollution brought by exterior gases should also be eliminated. Such exterior gases have two sources other than air; first, outgassing from photomask boxes fabricated with polymer materials and second, volatile gas produced by diminutive quantity of residual chemical solution on the surface of photomasks. These unexpected gases produce fogging effect on the surface of photomasks, make the photomasks unusable and become scrap, and thus increase the fabrication cost.
Therefore, to fill the photomask box with gas such as nitrogen or other inert gases is one of the methods to solve the problem of fogging effect on the photomasks. Yet how to speedily and effectively fill the above-mentioned gases into the photomask box so that the photomasks placed in the photomask box can be kept in isolation from the air and other exterior gases and transformation of photomasks due to contact with air can be avoided is a technique that currently needs to be further developed.